A number of cosmetic and personal care compositions have been utilized, particularly by women, to enhance and/or emphasize the appearance of keratin fibers, such as eyelashes. Such enhancements may include the impartation of color (or tone), volume (i.e., thickness), length and curl. Pre-formed fibers have been added to a number of mascara formulations for the purpose of enhancing the volume and/or length of eyelashes. Examples of mascara formulations containing pre-formed fibers are described in U.S. Pat. No. 6,726,917 (“the '917 patent”) and U.S. Pat. No. 6,656,487 (“the '487 patent”). The '917 patent provides a volumizing and/or lengthening mascara composition having pre-formed fibers, pigments, a water-soluble film former and an oil-soluble film former. The '487 patent describes a composition having pre-formed fibers and a copolymer having carboxylate groups and polydimethylsiloxane groups. The size of pre-formed fibers that can be incorporated into a mascara composition is limited by the viscosity and consistency of the overall mascara composition. In addition, mascara formulations having pre-formed fibers may form aggregates, which is visually unappealing and undesirable for a cosmetic formulation. Furthermore, pre-formed fibers contained within mascara formulations can often break from the eyelashes and fall into the eye, causing irritation, particularly for users with sensitive eyes or those who that wear contact lenses. In view of these practical considerations, pre-formed fibers incorporated into a mascara composition must be limited in length and thereby restricting the lengthening and/or volumizing benefits of adding pre-formed fibers to a mascara formulation.
There are a number of other methods for lengthening and/or volumizing eyelashes. One method for increasing appeared length and/or volume of eyelashes is by applying false eyelashes. False eyelashes are physical filamentous extensions applied onto an edge of an eyelid. Typically, false eyelashes include a base structure having pre-formed filaments extending therefrom. The base structure may be applied onto an eyelid with an adhesive. Application of false eyelashes is often difficult and cumbersome and may require the assistance of a professional makeup artist.
An alternative method used in the art for lengthening and/or volumizing eyelashes includes multiple applications of at least one cosmetic composition, where each application incrementally lengthens and/or volumizes the eyelashes. This lengthening and volumizing effect may be achieved by (1) multiple applications of a single composition or (2) multiple sequential applications of two or more different compositions.
In the first technique, a mascara formulation having a single composition is applied as a first layer to lengthen and volumize the eyelashes and left to set or dry. Subsequently, a second layer of the single composition is applied over the first layer. The second layer incrementally lengthens and/or volumizes the eyelashes in addition to that of the first layer. Application of the single composition may be repeated as many times as needed to yield the desired length and/or volume. Typically, these single compositions are wax-based and/or polymer-based, for example, PCT Application Publication No. WO 95/15741 and U.S. Patent Application Publication No. 2002/0168335, both of which disclose cosmetic compositions having wax and polymer.
In the second technique, a mascara formulation having two different compositions are applied alternately. A first composition, which is generally clear or white in color, is applied to eyelashes to lengthen and/or volumize the eyelashes and is allowed to set or dry. Once the first composition has set, a second composition, which is typically of a color such as black, brown, or blue, is applied over the first composition to further lengthen and/or volumize the eyelashes. Application of the first composition followed by the second composition may be repeated to incrementally lengthen and/or volumize eyelashes until a desired length or volume is reached. Examples of cosmetic formulations of the second technique include methods for applying a two-step mascara formulation by applying a washable mascara composition followed by applying a waterproof mascara composition, wherein the washable mascara composition, the waterproof mascara composition, or both may contain pre-formed fibers, such as, European Patent Application Publication No. 1516612 and U.S. Patent Application Publication No. 2005/0061349.
The aforementioned multiple-application techniques for lengthening and/or volumizing eyelashes are time-consuming and tedious because each layer provides only an incremental and gradual increase in length and/or volume. Between applying each additional layer, a user must wait for the previous layer to dry or set before applying a subsequent layer. Therefore, to noticeably enhance and/or emphasize the eyelashes, the user must apply multiple layers of the cosmetic formulation and wait for a period of time following each application to achieve the desired length and/or volume.
Liquid compositions comprising cross-linkable polymers are known in the industrial coating industry. These compositions may also include some type of cross-linkable chemical moiety within the structure of the cross-linkable polymer, as well as other ingredients such as solvents, dispersants, coalescents, and the like. These cross-linkable polymers are typically polymeric film formers and have been used in products such as paints, varnishes, lacquers, and the like. They are known to provide tough and resilient coatings.
Some cross-linkable compositions of this type are two-part, two-container systems, wherein a first part comprises the a first film forming polymer and a second part comprises a second film forming polymer cross-linkable with the first film forming polymer, and wherein the first part is physically separated from the second part just prior to use. Upon mixing the first part with the second part, such compositions then immediately react to form the cross-linked film coating. Alternatively, other systems are two-part, one-container systems, wherein the film forming polymer and the cross-linking agent are present in the same container. Blocking agents are typically included in two-part, one-container systems. The blocking agents inhibit the film forming polymers from cross-linking prior to use. The blocking agents are generally volatile agents. After a composition is applied to a desired substrate, a blocking agent therein evaporates and permits cross-linking of the film forming polymers.
Cross-linkable monomeric coatings have been used in the manufacture of artificial nail coatings, also known as “wraps” or “tips” to produce permanent coatings. For example, U.S. Pat. No. 4,104,333 teaches self-curing artificial fingernail compositions having cross-linking monomers. Upon application of the composition to a natural nail of a finger or toe, the monomers cross-link and form in situ a permanent, thick, artificial coating on top of the natural nail. If a lengthened artificial nail is desired, an extender is affixed to the end of the natural nail and the monomer composition is applied over the natural nail and extender and allowed to set or polymerize.
There is a continuing need in the art for cosmetic and personal care product, particularly mascara formulations, that overcome one or more of the foregoing deficiencies of conventional cosmetic products for lengthening or volumizing keratin fibers. It would be desirable to provide a cosmetic formulation and a method for lengthening or volumizing keratin fibers that is fast and effective without the cumbersome application of false eyelashes or tediously compounding incremental and gradual increases using a multiple-application technique. It would also be desirable to avoid the use of pre-formed fibers, which as discussed above, may break and cause eye irritation, and apply the in-situ polymerization technique from artificial nail coatings to keratin fiber lengthening and/or volumizing cosmetic formulations.
It is an object of the invention to provide a method for lengthening or volumizing keratin fibers, including eyelashes, eyebrows and hairs of the scalp.
It is further an object of the invention to provide a long-lasting cosmetic formulation for lengthening or volumizing keratin fibers, wherein the cosmetic formulation remains on the keratin fibers for an extended period of time.